The most important thing with fissures is to keep the stool soft, a texture similar to tooth-paste without taking the laxatives. If the stool softer than tooth-paste, it is an indication that you are eating food that is causing the stool to go soft in an unhealthy way, or there is something wrong with digestive system — which needs to be discussed with the physician.
During fissures or not, to keep the stool soft, one should increase the intake of fibres in diet, and increase the water intake as well. It is also important to avoid, or consume less food that makes the stool hard.